US3102233A

US3102233A - Galvanometer with discrete liquid globule damping means

Info

Publication number: US3102233A
Application number: US124048A
Authority: US
Inventors: Wilson A Charbonneaux
Original assignee: WACLINE Inc
Current assignee: WACLINE Inc
Priority date: 1961-07-14
Filing date: 1961-07-14
Publication date: 1963-08-27
Anticipated expiration: 1980-08-27

Description

Aug. .27, 1963 3 w. A- CHARBQNNEAUX GALVANOMETER WITH DISCRETE LIQUID GLOBULE DAMPING MEANS Filed July 14. 1961 2 Sheets-Sheet 1 IN VEN TOR.

WILSON A. CHARBONNEAUX ATTORNEY 1 r dALVANOMETER-WITH DISCRETE LIQUID stru-mentsf I L v u It is another object of the present invention to provide an instrument ofthe type. stated having damping means ing element.

" integrating pulsed meter input currents so that invention;

*' GLOBULE DAMPING MEANS Wilson A; Charbonn'caux, Dayton,, Ohio, assignor to WacLine, Inc-, Dayton, Ohio, a corporation of Ohio Filed July 14, 1961, Ser. No; 124,048 14Claimsb 324-425) This invention relatesin general to electrical indicating instruments and, more particularly, to"moving coil as semblie'sfin magnetic fields.

In many; volt meters, ammeters, ohm meters, and othertypes of galvanorneters and other indicating instruinents,,a moving coilisrotatablyg-rnounted within a magnetic field, This coil is usnally'inounted on some pivotpoint by meansof bearings or is suspended'from a t aut band, or wire. Sincefriction resulting fromzthe 1 "means of coil-suspension will intr'oduceeerious error, every efiort must be made to eliminate such friction.

However, when the means of coil suspensi on" is as frictionless as possible, the coil swings gvery fully and'beqqmeshighly susceptible to shock; vibration, and overiIn fact, damping problemsbecomeincreasingly more acute asthe amount offriction in the coil-bea ings" isreduced. p i

. -Normally, damping ofsuch a moving assemblyis ac v cover plate 4havin'g an enlarged circular apertureS bor dered by aninwardly extending flangef. Extending complished by one of fourj methods. First, "and'most generallyused, is'an aluminumwinding-form whichacts .as ashorted turn 'in whichitllle'induced current tends I to oppose the rotationof the coil in the magnetic fild.'-' N Secondly, the windings oftlre. coil are sometimes partially:

shont e'd'externally to provide a counter 'electromotiveF force which tends toretardirotation. A third method is touse anialuminum diskor segment which moves through the air gap of a strong magnetic field. Thelin duce'd eddy currents in the disk oppose rotation inproportion to speed. The fourth method is to useaflight vane in anair chamber which acts as adash-potto retard motion.

It is, therefore, one of the objects of the i ent invention to provide a. novel damping. means for trelatively swinging components such as, for example,

ew take-n 1 FIG. 3 is a sectionatviewltaken al gn -1t er;

FIG. "4 is a' fragmentary s daanai iew taken along line 4-4 of ,3," a i v FIG. '5 is-a fragmentary sectional view taken along 'lineS-S of FIG. 2;; V t t FIG. 6 is a vertical sectional view .of a modified form of nometer also constructed in accordance with and embodying the presentinvention; 1 Y

' FIG. 8"is a' fr'agmentary sectional vievwof a further modified form. or galvanometer embodying the present invention. 1 I V v I i I Referring nowin' rnore'det'ail and by reference characters to the drawings,v which illustrate practical embodi;

ments of'thef present-invention, A designates a galvario- -rneter comprising fan open-topped cylindrical metal housing 1 integrally including a flat rear. wallz'havinga forwardly presented face 3. Threadedly mounted on, and across, the open" front of the tubular housing :1 is a closurewise across the aperture 5 between thehousing 1 and the flange 6 is "at'ransparent glass plate 7, which: bears peripherally against a sealing ring interposed be-" tweeen the plate 7 andforward edge of the housing 1.

Provided for disposition within the housing 1 -is a permanent magnet 9 having a substantially "cylindrical gap lllwhich, in elfect, subdivides the inagnet9 into opposedpolejs 11, llconneoted by amagnet ic yoke .13

. The poles 11,12 are provided with

holes

14, 15 for accommodating elongated mounting bolts 16, 1 6', which also Sextend through spacer-sleeves" 1- 7, 18 19 and 17", I 18219, respectively, and through apertures inithebottom wall 2 fo-rjsecurement by

.nuts

20, 20; By this means, the magnet 9 rigidly mounted in properly spaced position within the housinglr Also 'suppor-ted' at its opposite ends between the heads of the bolts 16,-?16'and x the, spacer-sleeves 17, .17 is a non-magnetic support-bar the stationary core and moving coil-frame of a galvanometer or other similar of electrical reading inthat does not require added weight or inertia on the mov- ,It is another an instrument of the type stated having damping means which does not involve mechanical'friction or rnechanical limits.

It is also an object. ofthe present invention to provide "an'instrum-ent of the, type statedjinwhich the moving elementhas means for both axialand torsionaljdamping. It is a further object of the present invention tofprovide.

an eleotrical" meter of the typestated having means for average stable indicated readings may be "taken. It isan additional object of the present invention to object of the present inventiongtofprovide jeweled

bearings

25, 26, and held in endwiseadjustment;

21 which extends diametrally across the gap .10 in forwa'rdly spacedrelation to the forward face ofthe-magnet'.

9. Similarly supported at its opposite ends between the spacer-

sleeves

18, 19 and 1"8,19" is anon-magnetic" supporbhar 22 which also extends diam-etrally across the gap 10 in rearwardly spaced relation to the rear face of the magnet 9 and in parallelregistration with the support-bar 21. Moimted in the suppont s-bars zl, 22', in alignment with the'central axis of the' gap were

journal screws

23, 24, each provided with axiallyaligned by lock-nuts 27, '28, respectively.

7 provide a damping means on a meter of the type stated' that is? economical in cost, and rigid and sturdy injcon struction. I

" 'With the above and other o b jects inview, my. invenarrarigernent, and combination of parts presently dc scribed and pointed out. in the claims N Inthe accompanying drawings" (tvvosheets).,- v

FIG. 1 is a' perspective'wiew of agalvanometerconstructed in accordance with and embodyingfthe present t tron res des in the novel features of .form, construction,

Rotatably mounted in the vjeweledbearings 25, [16 is a loop-shaped coil 29 wound upon-a substantially rec-' tangular coil-form B0 integrally including channel-shaped frame-legs l '1 l l and being supported by two

pivot pins

31, 32 having tapered

points

33,34 for disposition inrthe bearings 25', 26. The coil 20 isnormal'ly lbiase dto a standardzero setting position by-th-e action ofjtwo counterbalancing

coil springs

35, 36, which are fastened at their inner ends to the

pivot pins

31, 32," respectively, and attached at their outer ends to

adjustment yokes

37, 38, respectively, which'are, adjustably'secured' upon the

journal screws

23, 2 4 bythe lock-nuts27, 28.

The coil 29is also conventionally provided with pigtail conductors r51 by which it is connected to the current 1 source to be measured. .Centrally of 'their interior faces, l the frame-legs are provided with inwardlypresented'arcm ate dimples d d which' are respectively coaxial with the

pivot pins

31, 32. If desired thejeweled bearings T tent New,

along line of 25, 26 can be set into cushioning springs or shockmounts which are conventional and, therefore, are not shown.

Rigidly secured to the forward leg I of the coil-form 30 and extending radially therefrom is an arm 3% integrally provided at its outer end with an offset bend 40 projecting forwardly through an arcuate slot 41 formed in a dial-plate 42 mounted across the housing 1 in rearwardly spaced close proximity to the glass plate 7. At its forward end, the offset-bend 40 is integrally provided with a needle or pointer 43 which moves across a conventional scale 44 imprinted upon the face of the dialplate 42.

Supported from the cylindrical side wall of the housing 1 by means of screws 45, 46 is a cylindrical magnetic core 47 which fits loosely with the coil-form 30 and is substantially coaxial with the gap 10. The forward and rearward end faces 48, 49 of the core 47 are arcuately crowned and the central areas thereof are located in close proximity to the dimples d d and, in the intervening spaces, are small discrete globules g g of a non-hygroscopic viscous liquid, such as a silicone polymer or other similar material which has a substantially stable viscosity over wide ranges of temperature.

In use, the coil 29 is energized through the pigtail connectors t t in the usual manner and the flux generated therein will interact with the magnetic flux across the gap 10 to produce a corresponding deflection of the coil 29 and the needle 43 which moves with the coil 29. In this respect, the galvanometer A operates in the usual manner. However, the rate of swing is very effectively clamped by the globules g g so that the coil will reach its indicative position precisely and with very little, if any, overswing or hunting.

Obviously, the degree of damping effect can be varied by selecting a liquid of higher or lower viscosity. A liquid of high viscosity will introduce a relatively high degree of damping effect and, correspondingly, a liquid of low viscosity .will introduce alow degree of damping effect. Moreover, it has been found in connection with the present invention that when the intervening spaces between the end faces 48, 49 of the core 47 and the dimples d d is of the order of ten to twenty thousandths of an inch, the globules 3 g will be held in coaxial alignment with the pivot pins 31, 32, by capillarity. Under such conditions, the globules g g will remain in such position, notwithstanding shock s, vibration, orchangein position of the galvanometer A. In fact, the globules g g will even remain in position under rather severe centrifugal and gravitational forces. The globules g g effectively damp both torsional and axial movement of the coil 29 and the damping force exerted by the globules is substantially constant at all times over all ranges of movement. It does not vary significantly in proportion to the speed or the degree of deflectional movement.

It is also possible to provide a modified form of galvanome-ter B which is illustrated in FIGS. 6 and 7 and is, in many respects, similar to the previously described galvanometer A. The galvanometer B comprises a housing 1' and a permanent magnet 9' having a cylindrical gap 10' and being held in place within the housing 1' by means of mounting

bolts

50, 50 and spacer-

sleeves

51, 52, 53, 51', 52', 53'. Supported at their ends by means of the bolts 50, 50' and spacer-

sleeves

1, 52, 53, 51', 52', 53' are dielectric support-bars 54, 55, which are substantially similar to the previously described support-

bars

21, 22, and extend diametrally across the gap in outwardly spaced relation to the opposite faces of the magnet 9'.

Theadedly mounted in and extending through the support-bar 54 in coaxial relationship to the cylindrical gap v10' is a journal cup 56 integrally including an externally threaded quill 57, a dish-shaped or concave bottom wall 58, and a cylindrical flange 59. Similarly mounted in the other support-bar 55 is a journal cup 60 which is also in ly comprises an externally threaded quill 61, a dish-shaped or concave bottom wall 62, and a cylindrical flange 63. Seated within the journal cups 56, 60 are two identical flat washer-

springs

64, 65 having central portions which are respectively located in coaxial alignment with the

quills

57, 61, and are capable of deflection in the axial direction.

Operatively disposed within the cylindrical gap 10' is a coil 66 which is wound upon a rectangular coil-form 67 integrally including four channel-shaped legs l l l I. The coil 66 and coil-form 67 are rotatably suspended within the cylindrical gap 10' by means of flat ribbons or so-called

taut bands

68, 69 formed preferably of Phosphor bronze or some other similar spring-forming material capable of torsional deflection. As will be seen by reference to FIG. 6, the

taut bands

68, 69 extend along the axial line of the cylindrical gap 10' and are rigidly attached at their inner'ends to the legs 1 l of the coil-form 67 and, at their opposite ends, to the central deflecting areas of the washer-

springs

64, 65. On their inwardly presented faces, the legs 1 l of the coil-form 67 are provided with dimples d d which are located in coaxial alignment with the

taut bands

68, 69, and are substantially similar in configuration and function to the previously described dimples d d Rigidly supported from the housing 1' and extending into the cylindrical gap 10' for loose-fitting disposition within the coil-form 67 is a cylindrical core 70 having arcuately crowned end faces 71, 72, the outermost portions of which are in opposed closely spaced relation to the dimples d d. In the intervening space between the end faces 7-1, 72 and the dimples d d are. discrete globules g g of a viscous damping liquid which are similar in purpose and function to the previously described globules A which is axially provided with arcuate protuberances d and a coil-form 30' having a flat underface. Held by capillarity between the protuberances d and the coilform 30' are globules g which act as damping agents and are substantially similar to the previously described globules'g g Other similarvariations may also be employed, the important factor being that the axial space between the coil or coil-form and the core or other comparable stationary element decreases inwardly toward the axis of rotation, asexemplified by the dimples d d d d and d for instance. The degree of curvature or decrease in spatial distance, of course, may be varied in accordance with the viscosity of the particular damping liquid selected.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the galvanometers may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A galvanometer of the type described, said galvanometer comprising a magnet creating a magnetic field, a movable electrical coil rotatably mounted in said magnetic field for rotation when energized and having a central aperture, a core mounted within the aperture of said coil, and a discrete liquid globule located along the axis of rotation of the movable coil and being operatively interposed between the movable coil and said core for damping the movement of the coil when said coil is electrically energized.

2. A galvanometer of the type described, said galvanometer comprising a magnet creating a magnetic field, a movable electrical coil rotatably mounted in said mag- I netic field for rotation about a selected axis, said coil coaxial alignment with the cylindrical gap 10' and integral- 75 interior region of said coil and supported by means exterior to said coil, and a discrete liquid globule located along said axis of the coil and being operatively interposed between said coil and said core for damping themovement of said coil with respect to said core.

3. A galvanometer as defined in claim 3, in which the liquid forming the discrete globule is a non-hygroscopic viscous liquid.

4. A galvanometer as defined in claim 3, in which the liquid forming the liquid globule is a silicone polymer liquid.

5. A galvanometer of the type described, said galvanometer comprising a housing, a magnet mounted within said housing and creating a magnetic field therein, a movable electrical coil rotatably mounted in said magnetic field for rotation about a predetermined axis, said coil having an interior open space that is accessible from a point exterior to said coil, said coil further having a surface which is presented inwardly toward said open space, a core mounted within said interior open space by means exterior to said coil, said core having an outwardly presented surface disposed in close proximate relation to said inwardly presented surface of the coil along said axis, and a discrete liquid globule interposed between said inwardly and said outwardly presented surfaces at the region of proximity therebetween along said axis.

6. A galvanometer of the type described, said galvanometer comprising a housing, a magnet mounted within said housing and creating a magnetic field therein, a movable rectangular coil integrally including four channel shaped frame legs and defining a central aperture, a pivot pin mounted in each of two leg frames for rotatably mounting said coil in said magnetic field, an inwardly concave dimple formed on the inwardly presented face of each of two said leg frames, a core mounted within the aperture of said coil, said core having arcuately crowned outwardly presented lateral side faces disposed in parallel relation to said inwardly presented faces, and fluid damping means interposed between said dimples and said arcuately crowned outwardly presented side faces for damping the movement of said coil.

7. A galvanometer of the type described, said galvanometer comprising a housing, a magnet mounted within said housing and creating a magnetic field therein, a movable rectangular coil integrally including four channel shaped frame legs and defining a central aperture, a pivot pin mounted in each of two leg frames for rot-atably mounting said coil in said magnetic field, an inwardly concave dimple formed on the inwardly presented face of each of two said leg frames in coaxial alignment with said pivot pins, a core mounted within the aperture of said coil, said core having arcuately crowned outwardly presented lateral side faces disposed in parallel relation to said inwardly presented faces, and fluid damping means interposed between said dimples and said arcuately crowned outwardly presented side faces for damping the movement of said coil.

8. A galvanometer of the type described, said galvanometer comprising a housing, a magnet mounted within said housing and creating a magnetic field therein, a movable rectangular coil integrally including four channel shaped frame legs and defining a central aperture, a pivot pin mounted in each of two leg frames for rotatably mounting said coil in said magnetic field, an inwardly concave dimple formed on the inwardly presented face of each of two said leg frames, a core mounted within the aperture of said coil, said core having arcuately crowned outwardly presented lateral side faces disposed in parallel relation to said inwardly presented faces, and discrete globules of a liquid interposed between said dimples and said arcuately crowned outwardly presented side faces for damping the movement of said coil.

9. A galvanometer of the type described, said galvanometer comprising a housing, a magnet mounted within said housing and creating a magnetic field therein, a movable rectangular coil integrally including four channel shaped frame legs and defining a central aperture, a pivot pin mounted in each of two leg frames for rotatably mounting said coil in said magnetic field, an inwardly concave dimple formed on the inwardly presented face of each of two said leg frames, a core mounted within the aperture of said coil, said core having arcuately crowned outwardly presented lateral side faces disposed in parallel relation to said inwardly presented faces, and discrete globules of a non-hygroscopic viscous liquid interposed between said dimples and said arcuately crowned outwardly presented side faces for damping the movement of said coil. i t

10. A galvanometer of the type described, said galvanometer comprising a housing, a magnet mounted within said housing and creating a magnetic field therein, a movable rectangular coil integrally including four channel shaped frame legs and defining a central aperture, a pivot pin mounted in each of two leg frames for rotatably mounting said coil in said magnetic field, an inwardly concave dimple formed on the inwardly presented face of each of two said leg frames, a core mounted within the aperture of said coil, said core having arcuately crowned outwardly presented lateral side faces disposed in parallel relation to said inwardly presented faces, and discrete globules of silicone polymer interposed between said dimples and said arcuately crowned outwardly presented side faces for damping the movement of said coil.

11. A galvanometer according to claim 5 and further characterized in that the space between the proximate surfaces of core and movable coil in the region of the axis about which such coil rotates decreases progressively toward such axis, such space, at the axis, being of capillary dimension whereby the liquid interposed in such space is held therein by capillarity.

12. A galvanometer according to claim 5 in which the core is crowned outwardly toward the coil in the region of the axis of rotation of said coil to provide said outwardly presented surface so that the space between the coil and the outwardly presented surface of the core progressively decreases toward said axis, the space between said crowned portion and coil at the axis being of capillary dimension.

13. A galvanometer according to claim 5 in which the outwardly presented surface of the core is formed by a projecting protuberance around the area coincident with the axial line of rotation of the coil.

14. A galvanometer according to claim 5 further characterized in that said coil is wound upon a coil-form which surrounds said core in spaced relation thereto and in which said inwardly presented surface is formed by inwardly projecting dimples which progressively narrow the space between the coil-form so that the distance between the coil-form and core along said line of axial rotation is of capillary dimension.

References Cited in the file of this patent UNITED STATES PATENTS 2,596,019 Fisher May 6, 1952. 2,623,083 Schlumberger Dec. 23, 1952

Claims

1. A GALVANOMETER OF THE TYPE DESCRIBED, SAID GALVANOMETER COMPRISING A MAGNET CREATING A MAGNETIC FIELD, A MOVABLE ELECTRICAL COIL ROTATABLY MOUNTED IN SAID MAGNETIC FIELD FOR ROTATION WHEN ENERGIZED AND HAVING A CENTRAL APERTURE, A CORE MOUNTED WITHIN THE APERTURE OF SAID COIL, AND A DISCRETE LIQUID GLOBULE LOCATED ALONG THE AXIS OF ROTATION OF THE MOVABLE COIL AND BEING OPERATIVELY INTERPOSED BEBETWEEN THE MOVABLE COIL AND CORE FOR DAMPING THE MOVEMENT OF THE COIL WHEN SAID COIL IS ELECTRICALLY ENER GIZED.